Fibrinogen is a well-established risk factor for cardiovascular diseases (CVD). Our research group has recently reported that gamma prime (gA/g') fibrinogen, a minor form of plasma fibrinogen, is associated with coronary artery disease. Biochemical studies indicate that gNg' fibrinogen has a different clot structure and different coagulation and fibrinolysis rates than the major fibrinogen form. The long-term goals of the proposed research are to understand the role of gA/g' fibrinogen in hemostasis, thrombosis and CVD pathogenesis. The specific aims of this proposal are: 1. To determine the relationships between gA/g' fibrinogen, cardiovascular disease and established risk factors for cardiovascular diseases. 2. To determine the effect of gA/g' fibrinogen on coagulation and on clinical laboratory assays. 3. To determine the relationships between gA/g' fibrinogen and other hemostatic factors. Relationships between clinical variables will be determined using cross-sectional studies, which are ancillary to large cohort studies. The results of the proposed research are necessary to develop a rationale working model for future studies of the role gA/g' fibrinogen in hemostasis, thrombosis and disease pathogenesis.